Rocket thrusting in space environments (e.g., at altitudes greater than 200 km above Earth's surface) has presumed that a propellant must be carried on board as a reaction mass (i.e., a fuel source). Related art space vehicles are typically propelled by carrying a reaction mass, chemically reacting or heating, or applying kinetic energy to, the mass and subsequently expelling the reacted mass, thereby propelling (i.e., thrusting) the space vehicle. Such related art propulsion systems usually comprise a fuel or reaction mass source and an energy source, which may be a chemical source, a photovoltaic source, a nuclear source, and/or a solar-thermal source.
Many spacecraft, specifically orbiting satellites operating in the near-Earth space environment (herein defined only for the purpose of discussion as being in the altitude range of 200 km to 1000 km above Earth's mean surface), require propulsion system operation to either maintain or adjust the spacecraft's altitude, the altitude and the velocity being affected by the presence of drag from residual atmospheric constituents. For example, the International Space Station (“ISS”) currently requires frequent propulsive reboosting that necessitates refueling with propellants. Orbital decay, due to atmospheric drag, presents a major life-limiting issue for satellites, especially for reconnaissance and remote sensing satellites, which cannot be feasibly refueled to replenish propellants expended during propulsive reboosting.
Further, a need exists for surveillance satellites to maintain a lower Earth orbit in order to improve resolution of optical imaging, radar imaging, and infrared imaging. Such lower Earth orbit inherently involves greater atmospheric drag. The related art counters atmospheric drag by either accepting the situation and allowing for normal orbital decay before reentry (i.e., a satellite design life of less than about five years) or by carrying on-board propellant to maintain orbital altitude and to thereby extend operating life. Other related art space propulsion systems have employed gravitational gradients and geomagnetic fields for attitude stabilization; however, these methods do not provide the net thrust that is necessary for altitude control.
Yet other related art space propulsion systems have proposed a “scooped” electric thruster in conjunction with a decreased on-board propellant load (i.e., the “aero-assisted” orbital transfer vehicle utilizing atmosphere ingestion, referring to prior art FIG. 1). Such scooped electric thrusters comprise a “scoop” (a large parabolic intake nozzle) 1 and an engine 2 having an inlet 3 for receiving the intake mass flow 4 and an outlet 5 for expelling the exhaust mass flow 6 (prior art FIG. 1). The scoop is required to compress the intake mass flow 4 and to direct it into the engine where it would be electrically heated or ionized and electromagnetically accelerated. Such scoops have been known to impart considerable drag, because they decelerate the intake mass flow 4. In order for such scoops to become operational, they must be light, deployable, and power-conservative. Inflatable structures and magnetic nozzles have been proposed to realize the development of a working scoop. Significantly, the scoop art does not suggest eliminating the scoop structure, eliminating the need for compressing the intake mass flow 4, nor using an ambient gas ionization level “as is” and without additional ionization of ambient neutral species.
“Ionic breeze” air purifiers use electric devices for moving ambient air; however, such devices are not known to have been applied to space propulsion systems nor has their use been suggested for use in the sparse atmosphere of the near-Earth space environment. Toy devices, known as “lifters,” use a tethered ion breeze device for lifting a light frame from the ground. Lifters have not been found to be practical for any significant transportation purpose, because they require substantially high voltage (e.g., >15 kV) for operation. Moreover, the ionic breeze devices being implemented in air purifiers, as well as toy lifters, rely on the relatively dense atmosphere found near Earth's surface; and they have not been suggested nor demonstrated for operation in the sparse atmosphere of the near-Earth space environment (i.e., in the altitude range of at least 200 km above Earth's mean surface). Although some recent experimental work has been performed using ion breeze engines for endo-atmospheric ion propulsion, such work has been shown to require a magneto-hydrodynamic slipstream acceleration for hypersonic flight to at least orbital velocities at the top of the atmosphere.
While photon reflection has been also used as a “mass-less” method for providing thrust (e.g., solar sails and laser levitation of particles), such thrust has been demonstrated as being extremely low, and any thrust vectoring as being limited to a 180° arc centered on the vector of incident radiation.
Therefore, a long-felt need remains for a system and a method which provide useful drag compensation, useful thrust, useful torque, and useful attitude control for a space or an aerospace vehicle, regardless of size, while eliminating the expenditure of any reaction mass being carried on board the craft for these purposes.